ECHINODERMATA. 
640 
the general characters of the genus Asterias, the Star-fish, properly so called ; and, in proportion as 
they deviate from the Five-rayed Star, their cceca and ovaries are more numerous. 
A. ruhens, is very common in the European seas. A. glacialis, is much larger, often a foot in diameter; and 
it has tufts of fleshy tubes round the bases of the spines on the body. A. aurantia, is still larger, and has the 
edges of the rays paved with osseous plates, bearing strong and moveable spines. Some, as A. paposa, have 
more than five rays. Some have the rays solid, and without the groove, and they are called OpMurce, because 
their rays have some resemblance to the tails of Serpents. These move by flexures of the rays, which have spines 
on the sides in some, and are covered with imbricated scales in others. In them the pores are between the bases 
of the rays. The only feet which these have are in fine short grooves round the mouth. By some authors they 
have been made a separate genus. Some have the rays branched, and of them some have the division near the 
end of the rays, and seldom repeated; but in others it begins at the base, and each divti^on is branched again 
and again, till the whole resembles a bunch of Serpents’ tails ; each branching is into so many lateral parts : there 
are two points at the base of each ray. Those branched ones have been called Gorgonocephalce, or Medusa’s 
Heads. 
Alecto, or Comatula, have five large articulated rays proceeding from a stony plate on the upper part of the 
disc ; their rays are often divided into two or three branches, and both rays and disc are furnished with articu- 
lated threads. The cavity of the body has a star-shaped mouth, and a tubular opening, both on the under side. 
Encrinus [the Encrinites], — 
Resemble the last, but have the plate on the disc prolonged to a stem of many articulations. They are named 
from the form of the stem, and the number of rays. Pentacrinus europceus, is the only species in the European 
seas ; but there are others in the tropical oceans. In a fossil state they are exceedingly numerous, and varied in 
their appearance. The fossil Entrochites are portions of the stems or branches of Encrinites. 
THE SECOND FAMILY OF THE PEDICELLATA. 
The Echinus [Sea Hedge-hogs, or Sea Eggs], 
These have the body covered with a crust of calcareous matter, in segments nicely adapted to each 
other, and perforated by regular rows of holes for the membranous feet. The crust is also pierced by 
a number of smaller holes with four membranous tubes, which seem to be the breathing apparatus ; 
and where not perforated, the crust is armed with broad spines, articulated upon tubercles, and move- 
able. The mouth is furnished with five flat, calcareous teeth, in a very complicated apparatus, and 
having strong muscles ; and, as these wear away at their cutting edges, they extend by growth at the 
opposite extremity. The intestine is long, and attached spirally to the interior of the crust. The five 
ovaries, which are edible, are arranged round the vent, in the separate openings. Their motions 
are slow ; and they feed upon the smaller shelled Mollusca and Crustacea, which they seize with their 
membranous feet. Great numbers of them, including many not now found alive, are met with in a 
fossil state, especially in the chalk, where they are usually filled with flint earth, the same as the i 
sponges. 
They are either regular or irregular, — the regular ones having the mouth in the middle of the under 
side, and the vent opposite ; and the others are irregular in proportion as they deviate from this 
character. 
Echinus, properly so called. — Figure generally an oblate spheroid, with two bands of apertures, dividing the i 
surface from the mouth to the vent into segments, resembling those formed by the meridians on a globe. Some I 
have the spines stout, with smaller ones at the base, and others have them slender. Among the latter, is E. escu- 
lentus, found in the European seas. It is about the size of an ordinary apple, closely set with short spines, gene- 
rally of a violet colour. The ovaries are of the same colour ; and in the spring months they are edible, and have 
a very agreeable flavour. 
They vary in shape, and in the number and arrangement, and also the form of the spines. Some are depressed, 
some compressed, some have the spines unequal, and one species, E. atratus, has the spines unequal and trun- j! 
cated, resembling small paving-stones. | 
None of the irregular ones have the two apertures of the body opposite to each other in the middle j 
of the under and upper sides. The spines upon them are straight and slender ; and the chief distinc- | 
tions are the number, arrangement, and extent of the holes for the feet. 
Chironeus, have the general form of the last, but the mouth and vent are both on the under side. * 
Nucleolites, have the vent above, but near the margin. i 
Galerites, have a flat base, and a conoidal body, with the mantle in the centre of the disc, and the vent near its 
margin. |ji 
Scutella, have the openings as in the last, but the form of the body much depressed, and disc-like. Some have | 
no openings to the crust but the pores, and in others again these seem to be obliterated, or at all events do not ' 
